Field of the Invention
The invention relates to a method for determining a deceleration of a motor vehicle from the vehicle brake system.
The requirements for modern brake systems for motor vehicles are becoming increasingly stringent now a days. For example, antilock braking devices, driving stability controllers, drive slip controllers and traction controls are making wheel-selective brake actions necessary. This is achieved by brake systems which have an electromechanical wheel brake actuator on each wheel, mounted on the wheel brake caliper such as those described in German Patent DE 196 15 186 C1.
A critical criterion for the effectiveness of such additional functions is that the current total deceleration of the motor vehicle be defined as exactly as possible. As long as the wheel rotation speeds are proportional to the vehicle speed, that is to say the wheels show no tendency to become locked and the wheel slip is thus negligible, the total deceleration is essentially defined by the deceleration by the vehicle brake, called the braking deceleration in the following text.
The braking deceleration is a function of the contact-pressure forces of the brake pads on the brake disk and, in the case of hydraulic servo-assistance, the pressures (which are directly proportional to the contact-pressure forces) in the wheel brake cylinders (brake pressures) can, in particular, also be used as function variables here. Knowledge of the precise relationship between the braking deceleration and the contact-pressure force is of major importance for modern brake systems.